Hundreds of Palestinians are expected to head to the border crossing between Gaza and Egypt on Saturday to take advantage of the first free passage out of the blockaded territory in almost four years.

The opening of the Rafah crossing was agreed by Egypt as part of the reconciliation deal it brokered between rival Palestinian factions Hamas and Fatah last month.

Men aged between 18 and 40 will be excluded from leaving Gaza without an entry visa to Egypt. All others will be able to pass without restrictions. The Rafah crossing will be open from 9am until 5pm daily, excluding Fridays.

Access into and out of Gaza has been highly restricted since Hamas took control of the territory in June 2007. Exit to Egypt has been sporadic and largely limited to people needing medical treatment and students. Many Gazans have family and business connections in Egypt, and a rush of people attempting to cross the border is expected.

Hamas welcomed the move by the Egyptian government. It was "a courageous and responsible decision which falls in line with Palestinian and Egyptian public opinion", said spokesman Fawzi Barhum in a statement. "We hope that it is a step towards the complete lifting of the siege on Gaza."

The Palestinian Centre for Human Rights said the opening of Rafah, while appreciated, "is not an alternative to the core issue, which is lifting the Israeli closure imposed on the Gaza Strip, opening crossings for commercial transactions and allowing the freedom of movement of persons ... through the outlets that are controlled by the Israeli occupation forces".

The Rafah crossing will only be open to the movement of people, not commercial traffic.

During Israel's stringent blockade of Gaza following Hamas's election victory in 2006, a black economy flourished based on the smuggling of goods through tunnels between Gaza and Egypt. Since Israel eased the economic siege almost a year ago under pressure from the international community, the tunnel-based economy has largely collapsed. However, the tunnels are still used to smuggle construction materials – banned by Israel – and weapons.

Israel warned that the opening of Rafah could lead to an influx of arms and militants into Gaza. "It is a dangerous development that could lead to weapons and al-Qaida smuggling in Gaza," said the vice prime minister, Silvan Shalom.

Israel is also concerned about Egypt's shift to a more sympathetic attitude towards Gaza since the former president, Hosni Mubarak, was forced out in February. Mubarak was an ally of Israel and many Palestinians and their supporters accused him of being complicit in the blockade of Gaza.

The opening of the border was intended "to ease the suffering of the Palestinian people in the Gaza Strip", an Egyptian foreign ministry spokeswoman, Menha Bakhoum, told the Jerusalem Post. "This is a sovereign Egyptian decision," not taken in consultation with any other country, she added.

Apart from Rafah, all other crossings from Gaza are into Israel, and are tightly controlled. The blockade had created a "prison camp" in Gaza, David Cameron said last July.

Meanwhile, 21 prominent Israeli leftwingers have issued an open letter supporting the Palestinian campaign for recognition of an independent state in September. "As Israelis, we avow that if and when the Palestinian people declares independence in a sovereign state to exist side by side with Israel in peace and security we shall support such declaration," the letter said. It also appealed for the international community to back recognition.

Former Israeli prime minister Ehud Olmert called on his successor to have the courage to make progress on a peace deal with the Palestinians, with a state based on the pre-1967 borders. President Barack Obama, in his speech last week, had "expressed a simple truth, which we simply cannot do without. The entire world ... unequivocally supports resolving our conflict with the Palestinians on the basis of the 1967 borders coupled with land swaps," Olmert wrote in a front-page piece for Israel's biggest selling daily, Yedioth Ahronoth.